Aspergillus fumigatus is a major human pathogen having a wide distribution in nature. Several types of disease are caused by this organism including immunologica and non-immunologic mediated forms. Diagnosis depends upon clinical radiological, mycological, physiological and histological findings. Serological detection of antibodies against extracts of the organism has also been found useful in diagnosis, but not definitive. This is thought to be due to the nature of the antigens used which are not entirely satisfactory for several reasons, but primarily because most of these preparations are relatively crude and uncharacterized. A careful attempt to prepare meaningful, characterized and standardized antigens is therefore warranted. Our approach has been to develop methods to isolate such antigens which are protein in nature. Isolation of protein antigens from fungi will also facilitate studies on their role in the pathogenesis of the disease itself. Culture filtrate, cell wall and cytoplasmic antigens will be extracted from strains of Aspergillus fumigatus. These antigens will be fractionated by gel filtration. One of the antigens obtained from culture filtrate having a molecualr weight of 150 daltons will be evaluated in serological methods. We will also extract protein antigens from cell wall membrane complex using enzymes, particularly proteases and other hydrolases. Relevant antigens will be fractionated and used to detect antibodies, in skin test and lymphocyte transformation.